Method and apparatus for dispensing particulate material



March 1, 1966 J. M. STOGNER 3,237,805

METHOD AND APPARATUS FOR DISPENSING PARTICULATE MATERIAL Filed Oct. 28,1964 2 Sheets-Sheet 1 INVENTOR JOEL M. STOGNER 4 am, Max, M r

ATTORNEYS March 1, 1966 J. M. STOGNER 3,237,805

METHOD AND APPARATUS FOR DISPENSING PARTICULATE MATERIAL 2 Sheets-Sheet2 Filed Oct. 28, 1964 INVENTOR JOEL M. STOGNER M fl w M BY ATTORNEYSUnited States Patent 3,237,8d METHOD AND APPARATUS FOR DISPENSINGPARTICULATE MATERIAL Joel M. Stogner, Duncan, Okla, assignor toHalliburton Company, Duncan, Okla, a corporation of Delaware Filed Oct.28, 1964, Ser. No. 407,088 7 Claims. (Cl. 2221) This invention relatesto a method and apparatus for dispensing particulate material at anaccurately controlled rate. In particular, the invention relates to amethod and apparatus uniquely adapted for metering the flow of finelydivided material such as ground bentonite.

In dispensing finely divided or ground particulate material, it isconventional to employ a receptacle having side walls which convergedownwardly to terminate in an opening. Even with the dischargefacilitating effect of the sloping side walls, it has often beennecessary to further facilitate the dispensing of particulate materialthrough the employment of means such as agitators or aerated portions ofthe sloping walls.

Quite unexpectedly, it has been found that a particulate material may bedispensed with sufficient accuracy for proportioning or blendingpurposes without resorting to arrangements such as those describedabove. Through this invention it has been discovered that particulatematerial may be converged generally toward a horizontal surface havingan aperture through which material is to be dispensed at selectivelyvaried rates. Gas such as air is flowed upwardly through this surfaceduring the dispensing operation. With this arrangement, the flow ofparticulate material through the surface aperture progresses at aconsistently predictable rate without the occurrence of apertureclogging or material bridging within the material housing means.

It has also been observed that this dispensing or metering concept isuniquely suited to the discharging of particulate material intoa jetlikestream of liquid issuing from a nozzle. In this application of theinvention, it might be thought that a vacuum produced through a venturieffect associated with the nozzle might be desirably employed to furtherfacilitate the flow of particulate material through the dispensingoutlet. However, it has been unexpectedly observed that such a vacuumwill produce undesirable fluctuations in the flow of particulatematerial.

In appreciation of the foregoing discoveries, it is an object of theinvention to provide a method and apparatus by means of which they maybe effectively employed in the accurate dispensing or metering ofparticulate material.

It is a further object of the invention to provide such a ngpthod andapparatus which enables the rate of flow of particulate material to beconveniently changed even during the dispensing operation itself.

Yet another object of the invention is to provide such a method andapparatus by means of which particulate material may be dispensed on asustained basis without clogging a dispensing outlet.

Yet another object of the invention is to provide such a method andapparatus which may be readily adapted to conventional particulatematerial dispensing structures.

It is likewise an object of the invention to provide such a method andapparatus which enables the convenient repair or replacement ofcomponent parts.

It is also an object of the invention to provide such a method andapparatus which effectively eliminates the need for more complexdispensing arrangements such as hoppers having converging or conicalwall portions through which particle flow facilitating gas isintroduced.

A still further object of the invention is to provide such 3,237,805Patented Mar. 1, 1956 a method and apparatus which entails relativelynominal expense and yet produces high operational efficiency.

In order to accomplish the foregoing objectives, there is presentedthrough this invention a method of dispensing particulate material whichcomprises the collecting of such material within containing means andallowing the material to both converge and gravitate downwardlygenerally toward an apertured, generally horizontal, porous andpermeable surface. Gas is flowed upwardly through the permeable surfacearound a surface aperture. The particulate material flows downwardlythrough the aperture while the gas is flowing upwardly through thepermeable horizontal surface. Barrier means are selectively positionedbeneath the surface aperture so as to regulate the rate of flow ofparticulate material through the aperture.

The apparatus employed in the practice of the invention foraccomplishing the aforenoted objectives includes material containingmeans having downwardly converging wall means. Generally horizontal,permeable surface means extends across an interior portion of thematerial containing means. Vertical passage means, extending through thesurface means, defines an outlet for particulate material disposedwithin the containing means above the surface means. Means are providedfor flowing gas upwardly around the passage means through at least aportion of the surface means. Means are also provided for selectivelyvarying the rate of flow of particulate material through the verticalpassage means.

In describing the invention, reference will be made to preferredapparatus and method embodiments illustrated in the appended drawings:

In these drawings:

FIGURE 1 provides a partially sectioned, schematic and elevational viewof a preferred apparatus comprising a hopper-like receptacle adapted toregulate the downward flow of particulate, finely divided material intoa horizontally flowing, liquid jet;

FIGURE 2 provides a partially sectioned, schematic, and transverseelevational view of the FIGURE 1 assembly;

FIGURE 3 provides an enlarged, horizontal section and schematic view ofthe FIGURE 1 apparatus as viewed along the section line 33 of FIGURE 2;

FIGURE 4 provides a fragmentary, partially sectioned, and verticalelevational view of a portion of the FIGURE 1 apparatus as viewed alongthe section line 44 of FIG- URE 3; and

FIGURE 5 provides a fragmentary, partially sectioned, and verticalelevational view of a portion of the FIGURE 1 apparatus as viewed alongthe section line 55 of FIGURE 3.

FIGURE 1 illustrates an apparatus embodiment which is specificallyadapted for the metering or accurately controlled dispensing of finelydivided material such as ground or powdered bentonite which iscommercially utilized as an additive in oil well cementing operations.

The apparatus shown in FIGURE 1 comprises a container or receptacle-likehousing 1. Housing 1 includes a generally frustoconical, downwardlyconverging wall 2, a generally cylindrical mounting base 3 and anoutwardly flaring, frustoconical upper lip 4.

A horizontally extending screen 5 extends across the upper portion ofwall means 2 as shown generally in FIGURE 2. Screen 5 may be removablysupported on an annular rim 6 which is secured to the wall 2.

A metering cartridge 7 is spaced beneath screen 5 and provides a centralaperture through which the fiow of bentonite or other particulatematerial is accurately controlled.

Metering cartridge 7 comprises an upper surface defining, porous andpermeable wall means or plate 8 which may be fabricated from airpermeable material such as commercially available, porous and permeablehigh density polyethylene. The pore size of this material is such as toallow a flow of air or gas therethrough but prevent the flowtherethrough of fine or powdered particulate material. The porous andpermeable material of the plate 8 may have a permeability on the orderof to cubic feet of air per minute per square foot of surface area ofplate 8, at a pressure differential across this layer of approximatelytwo inches of water pressure. As illustrated in FIGURES 3 through 5,permeable plate 8 is provided with a generally rectangular, centralaperture 9.

Cartridge 7 additionally includes a lower, impermeable wall means orplate 10 spaced beneath plate 8. Plate 10 is of the same shape andconfiguration as the upper, permeable plate 8. Lower impermeable plate10 may be fabricated of metallic material such as steel.

As shown in FIGURE 3, plates 8 and 10 each have circularly configuredouter edges.

An annular, outer metallic rim 11 and generally rectangular, metallicinner rim means 12 shown in FIGURE 4 serve to vertically space theplates 8 and 10 so as to define a generally annular cavity 13. As willbe appreciated, rims 11 and 12 sealingly interconnect the upper plate 8and the lower plate 10 and are fluid impermeable.

In order to effectively support the inner and outer edges of the plate 8and hold these edges in tightly sealed relationship against the rimmeans 11 and 12, an outer annular rim 14 and inner rim means 15 may beprovided. As illustrated, outer rim 14 is disposed above and in alignment with the rim 11 and is of the same configuration and size as thislatter rim. Generally rectangular rim means 15, which surround thecentral aperture 9 of plate 8, overlie and are of the same configurationas the rim means 12.

As illustrated, rims 14 and 11 and plates 8 and 10 may be interconnectedby conventional threaded fasteners 16. Rim means 15 and 12 and plates 18and 10 may be interconnected by conventional threaded fastening means17.

By reference to FIGURES 3, 4 and 5, it will be seen that lower plate 10includes a central, rectangular aperture 18 aligned with the aperture 9of the upper wall 8. The edge portions of the plates 8 and 10 encirclingthe apertures 9 and 18, in conjunction with the rim means 12 and 15,define central, vertically extending passage means 19 for dispensing ordischarging particulate material contained within the housing 1 abovethe permeable upper surface 8a of wall 8.

Metering cartridge 7 is removably supported within the container 1 on anannular rim 20 which encircles and is connected to the inner peripheryof the frustoconical wall 2. Cartridge 7 may be detachably secured tothe rim 20 by conventional threaded fastening means 21 as schematicallyshown in FIGURE 4. In this secured position, the upper permeable plate 8extends horizontally across an intermediate portion of the apparatus soas to define an annular, aerating or gasifying surace encircling thecentral passage 19. As will be apparent, the cartridge 7, in resting onthe supporting rim 20, in essence is connected with the wall 2 such thatparticulate material within the housing 1 above the surface 8 must flowthrough the central passage 19 in order to move beneath the cartridge 7.

Pressurized gas such as air is supplied to the annular space 13 by aconventional, pressurized air supplying arrangement as schematicallyshown in FIGURES 1, 3, 4 and 5. This air supplying arrangement maycomprise a conventional air pressure regulator 22, an air pressure gauge23, and a conduit T-fitting 24 which intersects and is connected to thewall means 2 in a conventional fashion as schematically shown in FIGURES1 and 3.

Flexible, conventional conduit means 25 and 26 extend from fitting 24 tocartridge inlet fittings 27 and 28 respectively. As shown in FIGURES 3and 4, conventional fittings 27 and 28 are connected to and intersectlower wall 10 and are symmetrically disposed on opposite sides ofcentral passage means 19. With this arrangement pressurized air suppliedfrom a conventional source through a supply conduit 22a flows underregulated control through the pressure regulator 22 and the meter 23 andthrough the fitting 24 and flexible supply conduits 25 and 26 to enterthe annular space 13 on opposite sides of the central passage means 19.This pressurized air then is diffused and flows vertically upwardlythrough the permeable plate 8 so as to aerate and fluidize particulatematerial contained within the housing 1 above the wall 8.

Means are provided for selectively adjusting the flow of particulatematerial through the central passage means 19. This flow adjusting meanscomprises a horizontal plate 29 mounted for horizontal sliding movementsacross the aperture 18. As illustrated in FIGURE 5, the horizontal plate29 is supported in notched portions of rails 30 and 31 so as to beslidable in surface engagement with edge portions of the lower plate 10adjacent the central passage 19. Fasteners 17 secure rails 30 and 31 toplate 10.

An operating rod 32 may be connected by conventional means such aswelding 33 to the underside of the plate 29 and have a portion 32a whichprojects generally horizontally away from the plate 29 as shown inFIGURE 4. Rod portion 32a intersects an apertured Wall portion 2a so asto terminate on the exterior of the Wall 12 as shown.

An operating lever 34 is connected by a conventional pivot joint 35between conventional spaced bracket plates 36a and 36b which are mountedupon the lower portion of the housing wall 2. A linkage 37 is connectedby a conventional pivot joint 38 to a mid portion of operating lever 34and is connected by a pivot joint 39 to the free end 32b of operatingrod 32.

The upper end of operating lever 34 is provided with a transverselyextending, flow rate indicating pointer 40. Pointer 40 is disposedadjacent a flow indicating, calibrated plate 41 which is mounted upon alip 42 extending from rim 4 as schematically shown in FIGURES 1 and 2.Plate 41 is calibrated such that the positioning of the indicator 40 onthe plate is indicative of the flow capacity of the central passage 19as determined by the position of the metering or flow controlling,barrier plate 29.

In a preferred arrangement, the particulate material dispensingapparatus of this invention is employed in conjunction with a jet-type,conveyor and mixing apparatus 43.

As shown in FIGURE 1, apparatus 43 includes a T-type fitting 44 which isconnected to a discharge conduit 45, with the flow axes of the conduit45 and the fitting 44 extending generally horizontally and in verticalalignment beneath the central passage means 19. A jet defining nozzle 46intersects a wall portion 47 of the T-fitting 43 and is adapted toproduce a jet-like formation 48 of pressurized liquid flowing generallyalong the central, horizontal axis of the fitting 44 and immediatelybeneath the downwardly gravitating path of particulate material fallingfrom the passage means 19. Pressurized liquid such as Water may besupplied to the nozzle 46 by conventional conduit means and pump meansnot shown.

An annular, collar-like flange 49 may be connected to the upper neck 44aof the T-fitting 44 and define a coupling portion to slidably receivethe cylindrical mounting portion 3 of the housing 1. If desired, anO-ring type seal 50 may be mounted on the cylindrical portion 3 so as tosealingly interconnect the cylindrical portion 3 with the interior ofthe flange 49.

As will be appreciated, the liquid jet 48 defined by the nozzle 46,through a conventional venturi elfect, will tend to produce a vacuum inthe zone between the jet 48 and the passage 19. Such a vacuum in thiszone may be relieved by providing apertures 2b and 2c in thefrustoconical wall 2 between the cartridge supporting rim 20 and thecylindrical housing portion 3 as shown in FIG- URES 1 and 2. Theseapertures may be disposed in alignment with the axis of sliding movementof the sliding plate 29.

Under operating conditions, the rate at which powdered particulatematerial such as bentonite is to be dispensed will be governed by theflow rate of pressurized water issuing from the nozzle 46. The flowindicating plate 41 may thus be calibrated with reference to water flowrates so as to provide indications of settings for the indicator 40which will provide the desired flow capacity with respect to powdered orparticulate material moving through the passage 19.

The flow rate of water through the nozzle 46 may be determined byconventional flow rate metering devices, not shown, and the pointer 40accordingly adjusted.

With the apparatus set with the plate 29 disposed to allow a desiredrate of flow through the outlet 19, particulate material such asbentonite may be deposited onto the sifting screen 5. The powderedmaterial may be deposited from individual bags or from a continuousmaterial feeding mechanism. The screen 5 prevents the passage ofundesirably large particles or material masses.

Prior to initiating the dispensing operation, pressurized gas such asair is supplied to the annular space 13 so as to provide an upward,diffused flow of material aerating gas issuing through the plate 8.

With a continuous flow of pressurized gas passing upwardly through theplate 8, particulate material within the apparatus 1 and above thesurface 8a will converge downwardly and flow evenly and smoothly and ata controlled and consistent rate through the outlet 19.

The powdered material, after passing through the outlet 19, gravitatesdownwardly to the water jet 48 where it is entrained and flows throughthe discharge conduit 45 to a desired work site.

By venting the wall 2 between the metering cartridge 7 and the jet 46,pulsations in powder fiow which would tend to be caused by a vacuumcondition in this zone are effectively avoided. In addition, thedisposition of the vents 2b and 20 allows a vacuum induced air flowdownwardly along opposite sides of the stream of material falling fromthe passage 19. The two downwardly converging air streams may have adesirable effect on the material flow by tending to confine it along theelongate direction of the rectangular passage 19.

Even over sustained periods of powder dispensing, there will be observeda continuously accurate flow of powdered material through the outlet 19at the desired flow rate.

During operations, and while particulate material is being dispensed,the flow rate of the outlet 19 may be adjusted merely by appropriatelymanipulating the lever 34 so as to change the position of the flowcontrolling, barrier plate 29 relative to the central passage 19.

If it should become desirable to remove the metering cartridge 7 forreplacement or service purposes, it is merely necessary to remove thefasteners 211, tilt the cartridge 7, and disconnect the flexibleconduits 25 and 26 from the coupling 24- or from the couplings 27 and28.

The freed cartridge 7 may then be removed from the apparatus forreplacement or service purposes. As Wlll be appreciated, of course,prior to removing the cartridge 7 the screen 5 will have been removedfrom its supporting rim 6.

In describing the mode of operation of preferred method and apparatusembodiments, major advantages of the invention have been demonstrated.

A principal advantage resides in the ability of the method and apparatusto accomplish accurate metering or control of particulate material flowon a sustained basis. It has been observed that the accuracy of thesystem is substantially independent, from a practical standpoint, of thefluctuations in particulate material height within the dispensing hopperwhich would ordinarily be encountered during a dispensing operation.

Another major advantage of the invention resides in the ability of therate of flow of particulate material to be selectively varied during thedispensing operation.

Other advantages of the invention include the ability to dispensematerial on a sustained basis without causing clogging of the variablecapacity dispensing outlet and without causing bridging of the materialabove the horizontal aerating surface.

Not to be overlooked are the advantages inherent in the ability of themetering cartridge to be easily removed from the apparatus for repair orreplacement and the unique simplicity with which the metering cartridgemay be installed in conventional hopper structures.

It is also significantly advantageous that accurate dispensing ofparticulate material may be accomplished over a sustained period withoutthe necessity of introducing flow facilitating gas through hopper sidewall portions.

An obviously significant advantage of the invention involves the nominalexpense of the apparatus.

Those skilled in the dispensing art and familiar with the disclosure ofthis invention will at once recognize that the invention is not limitedto the dispensing of a particular material such as bentonite, but isbroadly applicable to the dispensing of finely divided or powderedmaterials. It will also be apparent that the invention is not limited touse in conjunction with a jet-type mixer as disclosed, but is broadlyapplicable to a variety of particulate material dispensing operations.It will also be apparent that additions, deletions, substitutions orother modifications may be made with respect to the disclosed method andapparatus embodiments which would fall within the purview of theinvention as defined in the appended claims.

I claim:

l. A method of dispensing particulate material at an accuratelycontrolled rate, said method comprising:

collecting particulate material within frusto-conical containing means;

allowing said particulate material to gravitate downwardly and convergegenerally toward an apertured, generally horizontal, and permeablesurface;

flowing gas upwardly through said permeable surface and entirelyencircling a surface aperture, with said aperture being disposedcoaxially of said frustoconical containing means;

allowing material to flow downwardly through said surface aperture whilesaid gas is flowing upwardly through said permeable, horizontal surfaceand "while maintaining said material exposed to ambient pressure; and

selectively positioning barrier means beneath said surface aperture soas to regulate the rate of flow of particulate material through saidaperture.

2. A method as described in claim 1 additionally comprising:

flowing a jet of pressurized liquid through a space beneath said surfaceaperture, with said particulate material flowing downwardly through saidaperture; and

providing communication between said space and the atmospheresurrounding said containing means.

3. An apparatus for dispensing material at an accurately controlledrate, said apparatus comprising:

material containing means including downwardly converging,frusto-conical wall means and an upwardly facing, continuously open,material inlet;

generally horizontal, permeable surface means extending across aninterior portion of said material containing means;

vertical passage means disposed coaxially of said frustoconical wallmeans, extending through said surface means, and adapted to provide anoutlet for particulate material contained within said containing meansabove said surface means;

means for flowing gas upwardly and entirely encircling said passagemeans through at least a portion of said surface means; and

means for selectively varying the rate of flow of particulate materialthrough said vertical passage means. 4. An apparatus for dispensingmaterial at an accurately controlled rate, said apparatus comprising:

material containing means including downwardly converging wall means;generally horizontal, permeable surface means extending across aninterior portion of said material containing means, said surface meanscomprising centrally apertured, porous and permeable wall means;centrally apertured, impermeable wall means disposed beneath and spacedfrom said permeable wall means, side wall means connecting the outeredges of said permeable and said impermeable wall means in mutuallysealed relationship and connecting the edges of the central apertures ofsaid permeable wall means and of said impermeable wall means in mutuallysealed relationship so as to form vertical passage means extendingthrough said surface means and adapted to provide an outlet forparticulate material contained within said containing means above saidsurface means; annular rim means carried by said converging wall meansand adapted to provide a support means upon which said interconnectedpermeable and impermeable wall means are disposed; means for flowing gasupwardly around said passage means through at least a portion of saidsurface means, said means for flowing gas through said porous andpermeable surface means comprising conduit means connected with saidimpermeable wall means and communicating with the space between saidpermeable and said impermeable wall means and adapted to supplypressurized gas thereto; and means for selectively varying the rate offlow of particulate material through said vertical passage means. 5. Anapparatus for dispensing material at an accurately controlled rate, saidapparatus comprising:

material containing means including downwardly converging wall means;generally horizontal, permeable surface means extending across aninterior portion of said material containing means; vertical passagemeans extending through said surface means and adapted to provide anoutlet for particulate material contained within said containing meansabove said surface means; means for flowing gas upwardly around saidpassage means through at least a portion of said surface means; meansfor selectively varying the rate of flow of particulate material throughsaid vertical passage means; generally horizontally extending conduitmeans connected to said material containing means whereby particulatematerial gravitating through said passage means falls generallyvertically through an :apertured upper portion of said conduit meansinto the interior thereof; jet defining means adapted to define a jet ofpressurized liquid having a flow axis extending generally horizontallythrough said conduit interior in vertical alignment beneath particulatematerial gravitating through said passage means; and vent means in saidmaterial containing means beneath said passage means adapted to providecommunication between the atmosphere surrounding said materialcontaining means and the space between said passage means and said jetdefining means. 6. An apparatus for dispensing material at an accuratelycontrolled rate, said apparatus comprising:

material containing means including downwardly converging wall means;generally horizontal, penmeable surface means extending across aninterior portion of said material containing means; vertical passagemeans extending through said surface means and adapted to provide anoutlet for particulate material contained within said containing meansabove said surface means; means for flowing gas upwardly around saidpassage means through at least a portion of said surface means; andmeans for selectively varying the rate of flow of particulate materialthrough said vertical passage means and including horizontal plate meansmounted for horizontal sliding movement across said passage means, anoperating r-od connected to said plate means and having a portionextending generally horizontally away from said plate means andextending sli-dably through an apertured portion of said converging wallmeans, lever means having a lower end pivotally connected with saidcontaining means beneath said rod means, linkage means pivotallyconnected at one end to an intermediate portion of said lever means andpivotally connected at another end to said rod means, and indicatormeans carried by an upper portion of said lever means and adapted toindicate the flow capacity of said passage means. 7. An apparatus fordispensing material at an accurately controlled rate, said apparatuscomprising:

material containing means including downwardly converging,frusto-conical wall means; generally horizontal, centrally apertured,porous and permeable wall means extending across an interior portion ofsaid material containing means and having an outer edge of circularconfigurations adjacent said frusto-conical wall means; centrallyapertured, impermeable wall means disposed beneath and spaced from saidpermeable wall means; side wall means connecting the outer edges of saidpermeable wall means and said impermeable wall means in mutually sealedrelationship and connecting the edges of the central apertures of saidpermeable wall means and said impermeable wall means in mutually sealedrelationship; annular rim means carried by said converging frustoconicalwall means and adapted to provide a support means upon which saidinterconnected permeable and impermeable wall means are removablysupported; vertical passage means of rectangular, horizontal crosssection defined by the interconnected edges of the central apertures ofsaid permeable wall means and said impermeable wall means, extendingthrough said surface means, and adapted to provide a rectangular outletfor particulate material contained within said containing means abovesaid surface means; and screen means mounted on said material containingmeans above said passage means; means for flowing gas upwardly aroundsaid passage means through at least a portion of said surface means,said means including plural conduit means connected with said impereablewall means and communicating with the space between said permeable andsaid impermeable wall means on opposite sides of said passage means andadapted to supply pressurized gas thereto, horizontal plate meansmounted for horizontal sliding movement across said passage means inslidable en gagement with the underside of said impermeable wall means;means for selectively adjusting the position of said plate meansrelative to said passage means, said means including an operating rodconnected to said plate means and having a portion extending generallyhorizontally away from said plate means and extending slidably throughan apertured portion of said converging, frusto-conical wall means;lever means having a lower end pivotally connected with said containingmeans beneath said rod means; linkage means pivotally connected at oneend to an intermediate portion of said lever means and pivotallyconnected at another end to said rod means; and indicator means carriedby an upper portion of said lever means and adapted to indicate the Howcapacity of said passage means; generally horizontally extending conduitmeans connected to said material containing means whereby particulatematerial gr avitating through said passage means falls generallyvertically through an apertured upper portion of said conduit means intothe interior thereof; jet defining means adapted to define a jet ofpressurized liquid having a flow axis extending generally horizontallythrough said conduit interior in vertical alignment beneath particulatematerial gravitating through said passage means; and

vent means in said frusto-conical wall means beneath said passage meansadapted to provide communication between the atmosphere surrounding saidma terial containing means and the space between said passage means andsaid jet defining means, said vent means including a pair of openings insaid frustoconical wall means disposed in alignment With the axis ofsliding movement of said plate means.

References Cited by the Examiner UNITED STATES PATENTS 2,883,240 4/1959Hahl et. a1 302-29 2,965,268 12/1960 Baunrline 222193 3,202,461 8/1965Paton 222193 X 20 LOUIS J. DEMBO, Primary Examiner.

STANLEY H. TOLLBERG, Examiner.

3. AN APPARATUS FOR DISPENSING MATERIAL AT AN ACCURATELY CONTROLLEDRATE, SAID APPARATUS COMPRISING: MATERIAL CONTAINING MEANS INCLUDINGDOWNWARDLY CONVERGING, FRUSTO-CONICAL WALL MEANS AND AN UPWARDLY FACING,CONTINUOUSLY OPEN, MATERIAL INLET; GENERALLAY HORIZONTAL, PERMEABLESURFACE MEANS EXTENDING ACROSS AN INTERIOR PORTION OF SAID MATERIALCONTAINING MEANS; VERTICAL PASSAGE MEANS DISPOSED COAXIALLY OF SAIDFRUSTOCONICAL WALL MEANS, EXTENDING THROUGH SAID SURFACE MEANS, ANDADAPTED TO PROVIDE AN OUTLET FOR PARTICULATE MATERIAL CONTAINED WITHINSAID CONTAINING MEANS ABOVE SAID SURFACE MEANS; MEANS FOR FLOWING GASUPWARDLY AND ENTIRELY ENCIRCLING SAID PASSAGE MEANS THROUGH AT LEAST APORTION OF SAID MEANS FOR SELECTIVELY VARYING THE RATE OF FLOW OFPARTICULATE MATERIAL THROUGH SAID VERTICAL PASSAGE MEANS.